1. Field of the Invention
This invention pertains to methods and apparatus for filling the cavity of a tire and wheel with a closed cell polyurethane foam, producing a foam filled tire from a pneumatic tire and wheel that is load supporting.
2. Prior Art
Heretofore, polyurethane foam filled tires have been produced by an injection of a liquid of polyurethane constituents into a mold during mold spinning, forming a foam filled tire. The owner by assignment of the present invention is owner of a number of U.S. Pat. Nos. 4,855,096; 4,943,223; 5,906,836 and 6,165,397, that disclose foam filled tires manufactured by spin casting methods. In which spinning processed the tire outer surface and closed cell foam interior are formed in a single casting operation, providing a tire with a slick outer surface and a closed cell interior.
Another tire fill method has involved filling a rubber tire mounted on a wheel through the tire stem with a mixture of polyurethane constituents that then react within the tire, providing a tire fill that is very dense. There are, of course, other tire fill arrangements that provide for introduction of materials into a tire for flat-proofing a tire. Such uses involve introduction of a sealing material into a tire that has a puncture, and pressurizing the tire to cause the sealing material to flow into the puncture and harden, sealing the puncture.
Recent U.S. Pat. Nos. 7,066,724 and 7,105,113 issued to Danules, et al., show an apparatus and method, respectively, for filling a tire with a light weight polyurethane foam, providing flat-proof tire. The Danules, et al. patents provide apparatus and method for its use where polyurethane reactive materials are mixed in a static mixer and a nucleating gas is separately supplied into the mixed reactant materials. The mixture of reactant materials and nucleating gas are passed into a tire mounted to a wheel assembly through the valve stem or through a hole cut into the casting wall at the valve stem. The introduced reactant materials continue to react in the tire and wheel cavity, producing a foam that fills the tire and wheel assembly.
Distinct from the Danules patents, the present invention employs polyurethane reactive materials that, when mixed, produce, as a product of the reaction, a nucleating gas, and provide for passing the reacting mixed materials into the tire though a fill hose whose end is fitted between the tire side wall bead end and a wheel rim whereon the tire is mounted. In practice, a side of the tire and wheel is positioned flat on a table and the fill hose end is fitted between and across the tire bead and rim. As needed, the fill hose can be moved around the wheel hub during filling for uniformly filling the tire and wheel cavity. The preferred reactant materials for practicing the invention are selected to produce a close cell flexible foam that uniformly fills the tire and wheel assembly cavity.
Additionally, unique to the invention, where the size and weight of a tire and wheel have heretofore restricted, such as in a practice of the Danules patents that are directed to passenger car tires and wheels that have a relatively small cavity volume, the utilization by the process of the invention of multi-point injection of reactant materials around hub provides for rapidly filling even a tire having a large interior volume. In which practice of filling a tire that has a large interior volume, the volume of reactant materials are carefully selected and passed through the fill hose to rapidly fill of the tire and wheel cavity while the reaction process of the reactant materials is still proceeding. After a completion of the filling process, and removal of the discharge hose from between the tire side wall end and wheel rim, the invention provides a tire bead lifter that is operated to lift the tire bead into sealing engagement to the wheel rim. The tire bead lifter provides bead positioning to the rim, thereby containing the foam in the cavity during curing so as to produce a uniform fill, without voids or spaces, within the tire and wheel cavity with the closed cell polyurethane foam.